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Short-Term Investments (Details) $ in Thousands | Mar. 31, 2023 USD ($) item | Dec. 31, 2022 USD ($) item
--- | --- | ---
Short-term Investments |  |
Short-Term Investments |  |
Amortized Cost | $ 11,031 | $ 205,991
Gross Unrealized Gains | 3 |
Gross Unrealized Losses | (7) | (79)
Fair Value | $ 11,027 | $ 205,912
Number of short term investments in unrealized loss position for less than 12 months | item | 3 | 16
Aggregate value of short term investments in unrealized loss position for less than 12 months | $ 6,200 | $ 25,600
Corporate debt securities |  |
Short-Term Investments |  |
Amortized Cost | 6,082 | 16,508
Gross Unrealized Losses | (7) | (63)
Fair Value | 6,075 | 16,445
Treasury bills |  |
Short-Term Investments |  |
Amortized Cost | 4,949 | 5,983
Gross Unrealized Gains | 3 |
Gross Unrealized Losses |  | (3)
Fair Value | $ 4,952 | 5,980
Yankee securities |  |
Short-Term Investments |  |
Amortized Cost |  | 2,000
Gross Unrealized Losses |  | (1)
Fair Value |  | 1,999
U.S. agency bonds |  |
Short-Term Investments |  |
Amortized Cost |  | 3,000
Gross Unrealized Losses |  | (12)
Fair Value |  | 2,988
Reverse repurchase agreements |  |
Short-Term Investments |  |
Amortized Cost |  | 178,500
Fair Value |  | $ 178,500

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- Definition Amount of cumulative unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity) and investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5A -Subparagraph (b) -URI https://asc.fasb.org/extlink&oid=126970911&loc=SL120269820-111563 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563 + Details
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